Microorganisms degrading cyclic and short-chain alkanes under anoxic conditions

丙烷和丁烷是天然气和原油的重要成分。丙烷和丁烷通过全球估计有10,000个石油和天然气渗漏，或作为工业活动的结果进入生物圈。它们在这样的渗漏部位的碳循环中扮演着重要的角色，作为好氧和厌氧微生物的底物。虽然丙烷和丁烷的好氧降解已经得到了深入的研究，但对这些烷烃在缺氧条件下的降解知之甚少。菌株BuS5是目前唯一能在缺氧条件下降解丙烷和丁烷的纯培养菌。BuS5菌株是一种中温硫酸盐还原细菌，在系统发育上隶属于三角洲蛋白细菌的Desulfosarcina-Desulfo价球菌群。到目前为止进行的生理测试表明，它只能使用丙烷和正丁烷作为生长基质。本项目旨在以菌株BuS5为模式生物，对丙烷和正丁烷的厌氧降解过程有更深入的了解。主要目标是(A)对菌株BuS5的基因组进行注释和分析，重点放在烷烃活化/降解酶/途径上；基因组将通过F.Musat和S.Sievert接受联合基因组研究所(JGI)资助的项目获得；(B)对与短链烷烃生长的菌株BuS5进行蛋白质组学分析；以及(C)旨在纯化和表征丙烷和丁烷活化酶的酶研究。

Propane and butane are important constituents of natural gas and crude oil. Propane and butane reach the biosphere through a worldwide estimate of 10,000 natural oil and gas seeps, or as a result of industrial activities. They play a significant role in carbon cycling at such seepage sites, serving as substrates for aerobic and anaerobic microorganisms. While the aerobic degradation of propane and butane has been intensively studied, relatively little is known of the degradation of these alkanes under anoxic conditions. Strain BuS5 is up to now the only pure culture that can degrade propane and butane under anoxic conditions. Strain BuS5 is a mesophilic, sulphate-reducing bacterium, phylogenetically affiliated with the Desulfosarcina-Desulfococcus group of the Deltaproteobacteria. Physiological tests conducted so far have shown that it can use only propane and n-butane as growth substrates. The present project aims at obtaining a deeper understanding of the anaerobic degradation of propane and n-butane using Strain BuS5 as a model organism. The main objectives are (a) annotation and analysis of the genome of Strain BuS5 with a major focus on the alkane activation/degradation enzymes/pathways; the genome will be available through a project by F. Musat and S. Sievert accepted for funding at the Joint Genome Institute (JGI); (b) proteomic analyses of Strain BuS5 grown with short-chain alkanes; and (c) enzymatic studies aiming at the purification and characterization of the propane- and butane-activating enzyme.